There are a lot of reasons why it is a bad idea to pay a goalie $8.5m a season. The biggest reason is that you can get about the same performance for a lot less money.
Lundqvist for his career has an Even Strength Save Percentage (ESS%) of 0.929. On average he has faced about 1778 shots a season, 1392 at ES, 329 on the PK, and 57 on the PP. Compared to an average (i.e. 0.920) goalie, Lundqvist gives up about 14 fewer goals a year during ES play. We can ignore the PK, because goalies do not differ on the PK. We can also ignore the PP. I do think that goalies differ on the PP, but the number of shots faced in one season is too small to see a meaningful difference.
Over the last 3 years, the Rangers goalies (Lundqvist and Biron) have seen 4937 ES shots and given up 346 goals. The Rangers spent $7.6m in 2010-11 and 2011-12, and $8.2m in 2012-13. With the new contract, they are going to spend at least $9.5m a season on goalies for the foreseeable future.
Lundqvist is a 0.929 goalie, but his performance will vary from year to year. Some years, he might actually finish with an observed save percentage below 0.920 (his lowest season so far is exactly 0.920, this season so far he is 0.912). The probability that he finishes at or below 0.920 in a season of 1400 shots is 0.104. Conversely, the probability that he winds up above 0.920 is 0.896.
The Blues goalies individually are not as good as Lundqvist. Halak for his career is 0.925 ESS% and Elliott is 0.916. Collectively, over the last 3 years, the Blues goalies have an ESS% of 0.9222. Over that time frame, the Blues have given up 359 ES goals. The Blues are much better than the Rangers at preventing shots and Blues goalies have only faced 4612 ES shots.
In 2010-11, the Blues spent $5.7m on Halak, Conklin, and Bishop. In 2011-12 they spent $4.3m on Halak and Elliott. Last season it was $5.9m for Halak, Elliott, and Allen.
Elliott for his career is 0.916. But since coming to St. Louis, including this year, he is 0.935 on 1589 shots. The probability of that happening if he is still a 0.916 goalie is only 0.004. If he's 0.925 it is 0.08. So he's likely at least 0.925.
Halak by himself has a probability of finishing above 0.920 of 0.696. Elliott, if really a 0.925 goalie, by himself is also 0.696. However, the Halak/Elliott duo together has a probability of finishing above 0.920 of 0.908. AND is better than OR.
I think the Blues are on the right track with this 1A/1B approach. Collectively, over the last 3 years the Blues goalies were 0.922. However, in 2010-11, Conklin was terrible (0.891). Remove him and the remainder is 0.926. However, I think you can do about as well as the Blues for even less.
Save money with RIG
What's RIG? "Redundant Inexpensive Goalies". If the Blues are 1A/1B then RIG is 2A/2B/2C. RIG gives you better goaltending for less money. RIG relies on 3 fundamental facts:
1) Average goalies are plentiful and cheap.
2) The difference between an average goalie and an elite goalie is small.
3) Goalies vary a lot from season to season.
Sign 3 average goalies for around $1m each. What's the probability in any given year that 2A is below average? 0.5. Same for 2B and 2C. What's the probability that all three are below average? 0.125. So the probability that at least one of the three will be above average is 0.875. Nearly the same as Lundqvist.
Here's the beautiful part. If you know that a 0.920 goalie finishes above average, what is his expected save percentage? 0.925 How do I get that? Here's a 0.920 goalie facing 1400 shots 100,000 times
If you take out the below average seasons, here's what is left. The arrow is the expected result.
The expected result is 0.925. But RIG is even better than that
More statistical magic
There are eight different seasons you get with RIG.
One season where all three goalies are above average.
Three seasons where two goalies are above average.
Three seasons where one goalie is above average.
One season where all three goalies are below average.
0.925 is your expected save percentage for your best goalie in the three seasons where only one goalie is above average. In the three seasons where two goalies are above average, the expected save percentage of your best goalie is 0.929.
In the one season where all three goalies are above average, your expected save percentage of your best goalie is 0.930.
Even in the worst case scenario, the one season where all three goalies are below average, the expected save percentage of your best goalie is 0.918.
The composite expected save percentage for RIG is 0.926
In fairness to the Blues
If you work this magic on the Blues 1A/1B
Four different seasons
One where both are above their average.
One where Halak is above their average.
One where Elliott is above their average.
One where both are below their average.
When both are above their average, the expected save percentage for the better goalie is 0.933.
When one is above their average, the expected save percentage for the better goalie is 0.929.
When both are below their average, the expected save percentage for the better goalie is 0.922.
The composite expected save percentage for this 1A/1B is 0.928.
So the Rangers are spending $9.5m a year on Lundqvist and his backup. I'm spending $3m a year on RIG. The Rangers are expecting Lundqvist to give up 99 goals on 1400 shots. RIG would be expected to give up 103. $6.5m for 4 goals is a bad ROI.
On 1300 shots, the Halak/Elliott 1A/1B would expect to give up 94 goals. RIG gives up 96 goals but is $2.9m less each season.